iMac - Booting Issue

I have and iMac 500Mhz Slot loading Mac running OS X and this is the first time that I have turned it on in about two months and now I am trying to access some Photshop and Illustrator work that I did on it and now it won't Boot.

Issue:I turn Mac on and it chimes like always and loads with the apple displaying and then it initilizes with the blue progress bar and finishies then it just displays the multicolor disk in the corner and never goes to the log-In screen.